<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        span{
            margin-left: 40px;
        }
    </style>
</head>
<body>
    <div id="app">
        To Do Tist <input v-model = "val" type="text"> <button @click = "add">新增</button>

    <h2>正在进行<span>{{len}}</span></h2> 
    <ul>
        <li v-for = "(item,index) in arr" v-show = "!item.checked">
        <input v-model = "item.checked" type="checkbox">
        {{item.val}}
        <button @click = "del(index)">删除</button>
        </li>
    </ul>

    <h2>已经完成<span>{{arr.length-len}}</span></h2>  
    <ul>
        <li v-for = "(item,index) in arr" v-show = "item.checked">
        <input v-model = "item.checked" type="checkbox">
        {{item.val}}
        </li>
    </ul>
    
    
    
    </div>
    
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
    <script>
        new Vue({
            el:'#app',
            data:{
            val:'', 
            arr: []
            },
            //计算属性
            computed:{
                len(){
                    return this.arr.filter((item)=>{
                        return item.checked === false
                    }).length
                }
            },
            methods:{
                add(){
                    this.arr.push({
                        val:this.val,
                        checked:false
                    })
                this.val = " "
                },
            del(count){   
                this.arr.splice(count,1)
            }
        }

        })  
    </script>
</body>
</html>